“... instead restore the responsibility of choosing members to state legislatures.”
Who “votes” THESE people into office? How vulnerable are THEY to bribes and threats?
Good questions but here is the catch 22, as you know. Ask yourself your questions with the current in place method of election, and then ask yourself is selection appointment better or is election better. Then ask, why did the Founders set up selection over election for Senators. Then see post 31.